Liu Yongfa, Zhao Yizhu, Ma Jiran, Guo Siyan, Gao Xuyang, Wang Bin, Gong Lu, Lv Zengpeng, Guo Yuming
State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
Poult Sci. 2024 Dec;103(12):104255. doi: 10.1016/j.psj.2024.104255. Epub 2024 Aug 23.
This study aimed to investigate the effects of different glycine levels in low-protein diets on the growth, nitrogen deposition, and expression of intestinal amino acid and glucose transporters in broilers from 29 to 42 d of age, in order to determine the optimal glycine supplementation level. A total of 240 male broilers at 29 days old were randomly assigned to 5 groups: the control group with a crude protein level of 20%, and experimental groups with low-protein diets (LP130) containing 18% crude protein, supplemented with glycine to achieve standardized ileal digestible (SID) glycine + serine to lysine ratios of 134% (LP134), 140% (LP140), and 145% (LP145). The results showed that the LP134 group had similar growth performance and slaughter performance compared to the control group (P > 0.05), whereas other low-protein diet groups had significantly lower growth performance (P < 0.05). Regression analysis determined that the optimal ratio for SID glycine + serine to lysine was 137%. A dynamic model for glycine + serine requirements was established through binary regression analysis: y = 599.051 × BW + 8.381 × ADG (R = 0.998, P < 0.001). Feeding LP134, LP140, and LP145 diets significantly improved nitrogen deposition rates in broilers (P < 0.05). Low-protein diets significantly upregulated mRNA levels of bAT, EAAT3, and SGLT1 genes in the duodenum (P < 0.05). In conclusion, appropriate glycine supplementation in low-protein diets can enhance growth performance, and nitrogen deposition efficiency, and regulate the expression of intestinal amino acid and glucose transporters. The optimal ratio of SID glycine + serine to lysine in low-protein diets for broilers aged 29 to 42 d is 137%.
本研究旨在探讨低蛋白日粮中不同甘氨酸水平对29至42日龄肉鸡生长性能、氮沉积以及肠道氨基酸和葡萄糖转运蛋白表达的影响，以确定最佳甘氨酸添加水平。将240只29日龄雄性肉鸡随机分为5组：粗蛋白水平为20%的对照组，以及粗蛋白含量为18%的低蛋白日粮（LP130）实验组，补充甘氨酸以达到标准回肠可消化（SID）甘氨酸+丝氨酸与赖氨酸的比例分别为134%（LP134）、140%（LP140）和145%（LP145）。结果表明，LP134组与对照组相比，生长性能和屠宰性能相似（P>0.05），而其他低蛋白日粮组的生长性能显著较低（P<0.05）。回归分析确定，SID甘氨酸+丝氨酸与赖氨酸的最佳比例为137%。通过二元回归分析建立了甘氨酸+丝氨酸需求量的动态模型：y = 599.051×体重 + 8.381×平均日增重（R = 0.998，P<0.001）。饲喂LP134、LP140和LP145日粮显著提高了肉鸡的氮沉积率（P<0.05）。低蛋白日粮显著上调了十二指肠中bAT、EAAT3和SGLT1基因的mRNA水平（P<0.05）。总之，在低蛋白日粮中适当补充甘氨酸可以提高生长性能、氮沉积效率，并调节肠道氨基酸和葡萄糖转运蛋白的表达。29至42日龄肉鸡低蛋白日粮中SID甘氨酸+丝氨酸与赖氨酸的最佳比例为137%。
